New buildings in New York City will soon include bird-friendly glass, which could save tens of thousands of birds’ lives each year during the migratory season. The New York City Council passed Int. No. 1482-2019-B yesterday, making it the largest U.S. city to adopt bird-friendly legislation.

The bill requires that the exterior wall envelope and associated openings be constructed with bird friendly materials up to 75 feet above grade. Materials other than bird-friendly materials are not allowed to exceed a total of 10 square feet within any 10 feet by 10 feet square area of exterior wall below 75 feet above grade.  The law also specifies that in instances where a building renovation includes the replacement of all exterior glazing the alteration must comply with the updated building code.

The amendment to section 1403.8 of the New York City building code defines bird-friendly materials as “a material or assembly that has, or has been treated to have a maximum threat factor of 25 in accordance with the American Bird Conservancy Bird Collision Deterrence Material Threat Factor Reference Standard, or with the American Bird Conservancy Bird-friendly Materials Evaluation Program at Carnegie Museum’s Avian Research Center test protocol, or with a relevant ASTM standard.”

In addition, the exterior wall envelope and any associated opening installed adjacent to a green roof system on the same building must be constructed with bird-friendly materials up to 12 feet above the walking surface.

Exceptions to the law include instances where ground floor transparency is required by the New York City Zoning Resolution. In those cases transparent bird-friendly material with a UV-reflective pattern and a maximum threat factor of 27 should be used. Another exception is in areas of special flood hazard and shaded X-zones where flood-resistant glazing is proposed and ground floor transparency required. In those cases, transparent bird-friendly material with a UV-reflective pattern and a maximum threat factor of 36 should be used.

The law also requires that bird hazard installations regardless of height above grade and fly-through conditions located 75 feet or less above grade be construction with bird-friendly materials.

Bird hazard installations are defined as monolithic glazing installations that provide a clear line of sight on the exterior of buildings, including, but not limited to, glass awnings, glass handrails and guards, glass wind break panels or glass acoustic barriers. Fly-through conditions are defined as one or more panels of glass that provide a clear line of sight creating the illusion of a void leading to the other side at a distance of 17 feet or less, or a convergence of glass sides creating a perpendicular, acute or obtuse corner.

The bird-friendly glass bill passed by a vote of 43-3. It will take effect one year after it is signed by Mayor Bill de Blasio, whose spokeswoman told the Associated Press that he supports the legislation.

Dr. Christine Sheppard, Glass Collisions Program director for the American Bird Conservancy, responded to the bill’s passage, saying that bird-friendly building design shouldn’t be perceived as an add-on or an extra.

“Many strategies for controlling heat, light and even security can be bird-friendly strategies, too. These can be incorporated into almost any building style, but should be built into project design from the outset to minimize additional costs. That’s why this kind of legislation is so important,” she said in a statement.